Methods and machines for grinding crankshafts

ABSTRACT

A machine for grinding crankshafts has an annular carrier rotatable coaxially around a crankpin of a stationary crankshaft, and a pair of pulleys are mounted on the carrier in such a manner that one of them can be moved towards the axis of the carrier, and abrasive belt is trained around the pulleys with its abrasive surface facing outwards, and one of the pulleys is adapted to be driven, so that as the belt orbits with the pulleys around the crankpin the belt is driven in contact with the crankpin for the grinding operation. At the contact point, the back of the belt is in contact with one of the pulleys.

United States Patent inventor Eric Levesley Sheffield, England Appl. No.849.470 Filed Aug. 12, 1969 Patented Aug. 3, 1971 Assignee English SteelCorporation Limited Priority Aug. 27, 1968 Great Britain 40892/68METHODS AND MACHINES FOR GRINDING CRANKSHAFI' S 9 Claims, 1 Drawing Fig.

U.S. Cl 51/135 B24b 21/00 Field of Search 51/135- [56] References CitedUNITED STATES PATENTS 3,124,908 3/1964 Wingetal 51/140 PrimaryExaminer-Othell M. Simpson Attorney-Lowe and King ABSTRACT: A machinefor grinding crankshafts has an annular carrier rotatable coaxiallyaround a crankpin of a stationary crankshaft, and a pair of pulleys aremounted on the carrier in such a manner that one of them can be movedtowards the axis of the carrier, and abrasive belt is trained around thepulleys with its abrasive surface facing outwards, and one of thepulleys is adapted to be driven, so that as the belt orbits with thepulleys around the crankpin the belt is driven in contact with thecrankpin for the grinding operation. At the contact point, the back ofthe belt is in contact with one of the pulleys.

METHODS AND MACHINES FOR GRINDING CRANKSI-IAFTS This invention relatesto a machine for grinding crankshafts, more particularly with largediameter crankpins.

One object of the invention is to effect the grinding of a crankshaftwith the crankshaft stationary and with a grinding device orbitingaround the crankpin, thus avoiding any need to counterbalance thecrankshaft.

Another object is to keep down the size of the grinding device, so as tokeep down also the mass orbiting round the crankshaft.

A further object is to avoid the use of grinding wheels, because oftheir high cost, the. difficulties involved in handling them, and thedifficulty of maintaining accurate grinding without frequent trueing orreplacement of the grinding wheel.

Yet another object of the invention is to provide a grinding device withreadily interchangeable grinding means so that optimum stock removal andoptimum surface finish can be easily obtained.

According to the invention, a preferred embodiment of the machine forgrinding crankshafts comprises abase, pedestals for supporting acrankshaft, interconnected saddles carrying the pedestals andreciprocable on the base in the direction parallel to the lengthwisedirection of a crankshaft supported by the pedestals, cross-slidesbetween the pedestals and the saddles, an upright frame across the base,an annular carrier rotatable on the frame with the axisof the carrierparallel to the lengthwise direction of said, crankshaft supported bythe pedestals, power means for rotating the carrier about its axis, apair of pulleys extending to one side of the carrier and parallel to itsaxis, a flexible abrasive belt trained around the pulleys with itsabrasive surface facingoutwards, power means for driving one of thepulleys and means for moving one of the pulleys towards and away fromthe axis of the carrier to apply the belt in contact with the crankpinfor the grinding operation.

With a crankshaft supported-by the pedestals, and with a crankpin to beoperated on aligned .with the axis of the carrier and in the samegeneral plane as thev abrasive belt and pulleys, the carrier is rotatedaround the crankpin to cause the belt to orbit the same andsimultaneously the abrasive belt is driven around the pulleys; the onepulley being moved towards the axis of the carrier to bring the abrasivebelt into grinding contact with the crankpin around which the beltorbits.

The other pulley is preferably a driven one and said one pulley forapplying the abrasive belt to a crankpin is an idle pulley. The idlepulley maybe mounted for movement towards and away from the drivenpulley for adjusting the tension in the belt and for facilitatingchanging of belts. In addition, an idler jockey pulley may be providedfor tensioning the belt. The idle pulley is preferably very;largejrt'fdiametegas ompared with the driven pulley, and preferably has a serratedor otherwise treated periphery enhancing thedriving grip of the belt.The means for driving the driven pulley is conveniently an electricmotor also mounted on the carrier, with power supplied through pickuprings and sliding contacts at the interface between the carrier and theupright frame.

The belt-applying or idle pulley is preferably carried by a swingingplate with its axis the same'as the driven pulley, for withdrawal of thebeltwell clear of a crankshaft when transferring from one crankpin toanother.

Another and separate electricmotor may provide both for rotation of thecarrier and, when required, reciprocation of the saddles.

The pedestals are preferably provided with aligned bearings for thejournals of a crankshaft, the bearings being split lengthwise forinsertion and removal of the crankshaft jour nals and provided withclamping bolts or studsfor gripping the journals in the bearings, sothat a crankpin to be ground can be brought into coaxial alignment withthe carrier.

The preferred embodiment of machine according to the invention will nowbe described, by way of example only, with reference to the accompanyingdrawing, which is a perspective view of the machine with a crankshaft inposition for the grinding of one of its crankpins.

The machine comprises a base i, pedestals 2 for supporting a crankshaft3, a pair of saddles 4 interconnected by a shaft 5 and reciprocable onthe base in a direction parallel to the lengthwise direction of thecrankshaft, cross-slides 6 supporting the pedestals on the saddles, anupright frame 7 across the base, and an annular carrier 8 rotatablymounted on the frame in bearings (not visible). The axis of the carrier8 parallel to the lengthwise direction of the crankshaft, and anelectric motor 9 is provided for driving the carrier 8 through areduction gear 10 and a gearbox 11 preferably incorporated in the frame7). The motor 9 also effects reciprocation of the saddles 4 through alead screw 12.

The cross-slides 6, on which the pedestals 2 are bolted, are traversedby usual lead screws (not visible). These lead screws may be providedwith square-ends l3 engageable by any suitable handle, and withpositioning dials 14. The pedestals are provided with split bearings 15and cooperating clamping bolts or studs 16 for gripping the journals 1?of the crankshaft 3. As shown, a crankpin 18 to be ground is positionedin coaxial alignment with the carrier 8.

The carrier is provided with parallel guides 19 for a radiallyadjustable slide 20A carrying a pair of pulleys 21A, 2113 extendingparallel to the crankpin 18. A flexible abrasive belt 22 is trainedaround the pulleys with its abrasive surface facing outwards. A jockeypulley 23 is provided for tensioning the belt, and an electric motor 24drives the pulley 213 through a gearbox 25. Power is supplied to themotor 24 at the interface between the carrier 8 and the frame throughpickup rings '26 extending around the periphery of the carrier 8 andsliding contacts (not visible) housed in a box 27 on the frame 7. Thepulley 21A is an idle pulley, and has a serrated periphery 28 enhancingthe driving grip of the belt 22 therewith. The pulleys 21A and 23 arecarried by a plate 29 mounted to swing about the axis of the drivenpulley 213 to permit withdrawal of the belt 22 well clear of thecrankshaft when transferring from one crankpin to another. The plate 29being shown in its innermost position in which it is secured by a bolt30 passing through an arcuate slot 311 in the swinging plate. The jockeypulley 23 is mounted on a bolt 32 adjustable along a slot 33 in theplate 29, but a screw adjustment could be provided alternatively. Theslide 20A is movable along the guides 19 by screws (not visible), saidscrews being recessed into the carrier 8 and rotatable manually.However, a further motor (with gearbox) for driving the screws could beprovided on the carrier with power supplied through further pickup ringson the periphery of the carrier and cooperating sliding contacts in thebox 27.

The position of each of the crankpins 18 to be ground is adjusted untilit is coaxially aligned with the outer or operative face of the carrier8. Then, with the abrasive belt 22 in contact with the crankpin and theback of the belt in contact with the pulley 21A, the carrier is rotatedaround the crankpin and the belt is simultaneously driven around thepulleys 21A, 21B, 23, to effect grinding of the crankpin.

The belt 22 is light and the pulleys 21A, 21B, 23 and the other orbitingparts can be made light in weight as compared with a grinding wheel ofsufficient diameter for guiding crankshafts of comparable size.Furthermore, the belt 22 is readily replaceable and interchangeable, andis relatively inexpensive, regardless of the grit and grade, as comparedwith a grinding wheel. The belt 22 and pulley 21A are narrow enough tosuit the shortest crankpin likely to be encountered in a crankshaft ofcomparable size, and the crankshaft 3 may be moved axially, by movingthe saddles 4 (and with them the cross-slide 6 and the pedestals 2) bymeans of the lead screw 12 to grind the whole length of each crankpin.Greater movement of the crankshaft provides for transfer from onecrankpin to another, after the plate 29 has been swung to bring thepulley 21A and belt 22 clear of the intervening crankwebs.

' pump, supply pipes and rains (not shown) circulate coolant,

which is cleaned by a centrifuge or a magnetic separator.

Additional operational attachments may be provided on the carrier 8,e.g., means carried by another slide 208 between the guides 19, forgrinding and polishing the faces of the crankweb and the fillet betweensaid crankwebs and the crankpins. Advantageously, this additionaloperation can be carried out simultaneously with grinding and polishingof the crankpin in accordance with the teaching.

l claim:

1. A machine for grinding the crankpins of crankshafts comprising:

a base,

pedestals for supporting a crankshaft,

interconnected saddles carrying the pedestals and reciprocable on thebase in the direction parallel to the lengthwise direction of acrankshaft supported by the pedestals cross-slides between the pedestalsand the saddles,

an upright frame across the base,

an annular carrier rotatable on the frame with the axis of the carrierparallel to the lengthwise direction of a crankshaft supported by thepedestals,

power means for rotating the carrier about its axis,

a pair of pulleys extending to one side of the carrier and parallel toits axis,

a flexible abrasive belt trained around the pulleys with its abrasivesurface facing outwards to engage the crankpins,

power means for driving one of the pulleys and means for moving one ofthe pulleys towards and away from the axis of the carrier to applythebelt in contact with the crankpin for the grinding operation.

2. A machine as in claim 1, wherein the other pulley is a driven one andthe pulley for applying the abrasive belt to a crankpin is an idlepulley.

3. A machine as in claim 1, wherein a jockey pulley is provided fortensioning the belt.

4. A machine as in claim 2, wherein the idle pulley is very large indiameter as compared with the driven pulley.

5. A machine as in claim 2, wherein the idle pulley has a serratedperiphery.

6. A machine as in claim 1, wherein the means for driving the drivenpulley is an electric motor also mounted on the carrier, pickup ringsand sliding contacts being provided at the interface between the annularcarrier and frame to supply power to said motor.

7. A machine as in claim 2, wherein the belt-applying pulley is carriedby a swinging plate with its axis being the same as the driven pulley topermit withdrawal of said belt well clear of a crankshaft whentransferring from one crankpin to another.

8. A machine as in claim 6, wherein a separate motor provides power bothfor rotation of the carrier and reciprocation of the saddles.

9. A machine as in claim 1, wherein the pedestals are provided withaligned bearings for receiving the journals of a crankshaft, thebearings being split lengthwise for insertion and removal of thecrankshaft journals and clamping bolts or studs for gripping thejournals in the bearings.

1. A machine for grinding the crankpins of crankshafts comprising: a base, pedestals for supporting a crankshaft, interconnected saddles carrying the pedestals and reciprocable on the base in the direction parallel to the lengthwise direction of a crankshaft supported by the pedestals cross-slides between the pedestals and the saddles, an upright frame across the base, an annular carrier rotatable on the frame with the axis of the carrier parallel to the lengthwise direction of a crankshaft supported by the pedestals, power means for rotating the carrier about its axis, a pair of pulleys extending to one side of the carrier and parallel to its axis, a flexible abrasive belt trained around the pulleys with its abrasive surface facing outwards to engage the crankpins, power means for driving one of the pulleys and means for moving one of the pulleys towards and away from the axis of the carrier to apply the belt in contact with the crankpin for the grinding operation.
 2. A machine as in claim 1, wherein the other pulley is a driven one and the pulley for applying the abrasive belt to a crankpin is an idle pulley.
 3. A machine as in claim 1, wherein a jockey pulley is provided for tensioning the belt.
 4. A machine as in claim 2, wherein the idle pulley is very large in diameter as compared with the driven pulley.
 5. A machine as in claim 2, wherein the idle pulley has a serrated periphery.
 6. A machine as in claim 1, wherein the means for driving the driven pulley is an electric motor also mounted on the carrier, pickup rings and sliding contacts being provided at the interface between the annular carrier and frame to supply power to said motor.
 7. A machine as in claim 2, wherein the belt-applying pulley is carried by a swinging plate with its axis being the same as the driven pulley to permit withdrawal of said belt well clear of a crankshaft when transferring from one crankpin to another.
 8. A machine as in claim 6, wherein a separate motor provides power both for rotation of the carrier and reciprocation of the saddles.
 9. A machine as in claim 1, wherein the pedestals are provided with aligned bearings for receiving the journals of a crankshaft, the bearings being split lengthwise for insertion and removal of the crankshaft journals and clamping bolts or studs for gripping the journals in the bearings. 